By Chris McKhann , analyst at OptionMonsterPEORIA, Ill. ( TheStreet) -- The big option trade of the day for Caterpillar ( CAT) appears to be a bet that the stock won't fall back to where it found support just a month ago. CAT was up 0.46% on Tuesday, finishing the session at $59.18. It remains below the 52-week high of $64.42 set on Jan. 11 but recovered nicely from support down near $50, where the price was a month ago. OptionMonster's real-time systems detected one block of 25,000 of the August $52.50 puts traded for $2.92. This was against open interest of just 2,608 contracts, so this was clearly a new opening position. The puts appear to have been sold, indicating that the seller doesn't think shares will return to that level before the August expiration. If it does drop back to the $52.50 strike price, the trader will be required to buy 2.5 million shares of CAT at that level. At the time of publication, McKhann had no position in the stock mentioned.